Rapamycin Impurity 2

(S)-(2R,3S,6R,7E,9R,10R,12R,14S,15E)-9-hydroxy-1-((1S,3R,4R)-4-hydroxy-3-methoxycyclohexyl)-10-methoxy-2,6,8,12,14-pentamethyl-5,11,17-trioxoheptadeca-7,15-dien-3-yl 1-(2-((2R,3R,6S)-2-hydroxy-6-((S,E)-2-methoxy-3-methyl-5-oxopent-3-en-1-yl)-3-methyltetrahydro-2H-pyran-2-yl)-2-oxoacetyl)piperidine-2-carboxylate